1. Field of the Invention
The present invention relates generally to satellite communications, and more particularly to satellite-based network routers.
2. Background of the Invention
For several decades, satellites have been an integral part of communication systems. Inherent to such communication systems is the need for routing signals and/or messages to their appropriate destinations. Until recently, routing functions have always been accomplished using ground-based routers, with a satellite acting only as a xe2x80x9cmirrorxe2x80x9d, reflecting uplink traffic back to a ground-based central station. It is this central station which performs the routing of messages to their appropriate destinations. Using ground-based routing, however, requires traffic to go through land lines, such as fiber-optic cables. As a result, the rate of transfer of information is significantly decreased.
Recently, a new generation of satellites have been introduced which act not only as uplink traffic xe2x80x9cmirrorsxe2x80x9d but perform the routing functions themselves, thus becoming, space based routers. Space-based routers must support a large number of ports. Ports are analogous to doorways into and out of a router system. Port types comprise input, output and bi-directional ports. The communications system interacts via radio waves, which fall within an allocated spectrum of frequencies. It is the nature of these systems to reuse an allocated spectrum as many times as possible. Multi-beam, phased array antennas are implemented to reuse an allocated spectrum many times over. Spectral reuse is achieved by forming as many uplink and downlink beams as size, weight and power, of a particular satellite, permit. As such, beams themselves become ports to and from the router. There can be hundreds and even thousands of ports resulting from the spectral reuse design. Additional ports for the router are formed from crosslinks between satellites within a constellation of satellites.
Earlier generations of these satellite based routers implemented hardware switches to perform the routing function. Hardware switches, however, are limited in bandwidth and centralize the routing process. This makes the routing process more susceptible to failures. Also, in order for such a system to grow or change its routing scheme, the hardware switches require redesign. This would require the satellite to be brought back to earth for modification or replacement by a completely new satellite.
It is therefore desirable to provide a routing architecture, for space-based routers, which overcomes the limitations of reduced bandwidth and decentralizes the routing process. It is also desirable to implement a routing architecture whose components do not require redesign to allow for scaleable growth or routing scheme changes.